Ohm's law calculator
Calculate voltage, current or resistance with Ohm's law, plus the circuit power.
Voltage
12 V
Power24 W
Fill in the two known values according to what you chose to calculate.
How the calculation works
Ohm's law relates voltage, current and resistance: V = R × I, giving I = V/R and R = V/I. Power is P = V × I.
Frequently asked questions
What is 1 ohm?
It is the resistance that lets 1 ampere flow under 1 volt.
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Updated on June 18, 2026 · by Rafael Rossi · Methodology & sources